User Guide for SIEMENS models including: Direct DC bias in Transformer, Direct, DC bias in Transformer, Transformer

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Transformer DCD manual-pdf Original file
Direct Current Detector
Detecting DC bias in transformer

siemens-energy.com/gt-service

Introduction
Understanding the impact of DC bias on transformers
DC bias significantly increases noise and loss levels in transformers. This DC can originate from power electronics in the grid, HVDC interconnections, renewable power generation, or small direct currents caused by geomagnetic effects. Due to the magnetic properties of transformer cores, even a small DC bias can lead to substantial consequences, including increased reactive power current requirements and greater losses.
For example, a mere few hundred milliamperes of DC can result in a notable increase in noise and no-load losses. A DC level of 500 mA may cause an increase of 13 dB(A) compared to reference noise levels in a test field without DC. The human ear perceives a 10 dB increase as a doubling of the noise level. Additionally, DC loading can lead to an increase of up to 50 percent in no-load losses.

early detection of DC bias. By providing a quick and easy initial assessment, the DCC enables users to identify potential issues before they escalate, ensuring the reliability and efficiency of transformer operations.
· Easy to use for any person at side · Giving a first actual indication of DC in the asset · Freely available for Android and IOS smartphones
How to perform a DCD measurement
The easy-to-use app transforms any smartphone into a DC detection device and can be used by any person at the site, either with or without internet connection. Below are the steps for performing a DCD measurement, presented with accompanying screenshots for clarity.

Therefore, it is essential for transformer owners, operators, and service personnel to detect DC bias in their transformers. The Direct Current Detector (DCD) app provides an initial indication of whether a transformer is affected by DC bias.
In case a transformer consistently shows DC bias, we strongly recommend contacting our Siemens Energy Transmission Service experts for a comprehensive diagnosis and tailored service recommendations. (Link to contact form.)
Features

1. Install the DCD app

To begin the DCD measurement, access the Direct Current Detector (DCD) app by opening the link.(see also QR-code) in your smartphone browser. Once the app is open in your

browser, tap

or

button and the "Add to Home

Screen" button

(the exact word-

ing may vary depending on your browser). This will save the

DCD app to your home screen for easy access,

allowing you to launch it directly from

your mobile device.

The Direct Current Detector (DCC) is designed to empower transformer owners and operators with essential tools for

© 2025 Siemens Energy

2. Read and confirm the license agreement

6. Follow up if necessary

Before proceeding, please review the "End User License Agreement for Free of Charge Mobile Applications" and the "Additional Conditions for Free of Charge Apps." These documents outline the terms and conditions associated with the use of the DCD app. Kindly confirm that you have read and understood the agreement before continuing.
3. Read the safety manual before DCD measurement

If the app indicates the presence of DC bias, we recommend contacting Siemens Energy Transmission Service experts for a thorough diagnosis and actionable service recommendations. (Link to contact form.)

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3

To ensure safe operation during the DCD measurement, please click on the Hamburger menu () and select "Safety."

Please read the Safety Disclaimer carefully before approaching a transformer for DC measurement. Understanding these safety guidelines is crucial for conducting the measurement safely and effectively.

4. Start DCD measurement

To begin your DCD measurement, click on "Start Your First Measurement." You will be prompted to select or enter the following details: substation name, serial number, and transformer name/label.

Next, select the microphone option, and initiate the sound

measurement by tapping on the microphone icon.

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Hint: For a high-quality initial assessment of DC effects, we

recommend conducting three measurements of 60 seconds

each. During the 60-second recording phase, walk around

the transformer while keeping your smartphone at a

distance of 30 to 100 cm from the transformer.

To ensure accurate results, avoid ambient noise during the recording, as it can negatively impact the DC assessment. The app will indicate recording quality using a traffic light system, and if necessary, it will provide further recommendations for improving sound quality.

5. Review measurement results

While the recording is in progress, the app will display the

following information:

· Hz: This indicates the sound frequency detected

during the recording, representing the Hertz of the

transmission grid.

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· Audio Signal: This provides an indication of sound

quality, categorized as "Poor," "Fair," or "Good."

· DC Detected/Not Detected: This shows the result

of the DC assessment, indicating whether Direct

Current has been detected.

Once the recording is complete, the app will process the audio file. A clear color signal will indicate the status of DC bias detection:
· Green: Everything is okay; no DC bias detected. · Yellow: An uncertain signal; further investigation
may be needed.
· Red: DC bias is detected; immediate attention is required.

© 2025 Siemens Energy

Published by © 2025 Siemens Energy Grid Technologies Service Humboldtstr. 64 90459 Nuremberg, Germany
Customer Support Center Phone: +49 911 6505 6505 E-Mail: support@siemens-energy.com
For more information, please visit our website:
siemens-energy.com/gt-service
"Subject to changes and errors. The information given in this document only contains general descriptions and/or performance features which may not always specifically reflect those described, or which may undergo modification in the course of further development of the products. The requested performance features are binding only when they are expressly agreed upon in the concluded contract."
Siemens Energy is a trademark licensed by Siemens AG.

© 2024 Siemens Energy

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